Tsugi wa Ii yo ne, Senpai次はいいよね、先輩; Seventeen Again

Mao, who had repeated a year for some reason, decided to start over in the second year of high school. Hachiya, a junior high school boy in the soccer club, became in the same class as Mao who repeated a year. Even though he is in the same grade as her he doesnt break his honorifics, in which Mao found difficult, but source: https://www.mangaupdates.com/series/ahw5kdz/tsugi-wa-ii-yo-ne-senpai